Fix CI failures and switch to official uv action

[agriyakhetarpal]

The uv action is failing on recent PRs because it is not able to find the uv executable. Astral has now adopted the action and moved it to their organisation; we should update and use it from there.

[Saransh-cpp]

@santacodes would you want to write a quick fix for this?

[santacodes]

@santacodes would you want to write a quick fix for this?

I was already on it, the problem with astral-uv action was it didn't have an innbuilt venv support and caching. Would that be a problem? Because then it would mean we write creating and activating venv environment in CI. A potential solution again for that might be using the nox GitHub action and using nox with the uv backend.

I also opened an issue upstream for reference - yezz123/setup-uv#98

[agriyakhetarpal]

I see, I didn't know caching was not enabled. I think it's actually not a big problem, since the local network speeds for GHA runners are fast enough to download dependencies quickly – the benefit is in fast resolution and installation times. I would be okay to proceed without caching.